﻿using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace ZhiAo.CommonLibrary
{
    public class Security
    {
        private string MD5Key = "";

        private string MD5Decrypt(string pToDecrypt)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
            for (int x = 0; x < (pToDecrypt.Length / 2); x++)
            {
                int i = Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 0x10);
                inputByteArray[x] = (byte)i;
            }
            des.Key = Encoding.ASCII.GetBytes(this.MD5Key);
            des.IV = Encoding.ASCII.GetBytes(this.MD5Key);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            StringBuilder ret = new StringBuilder();
            return Encoding.Default.GetString(ms.ToArray());
        }

        private string MD5Encrypt(string pToEncrypt)
        {
            try
            {
                string sKey = this.MD5Key.Substring(4, 8);
                DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
                des.Key = Encoding.ASCII.GetBytes(sKey);
                des.IV = Encoding.ASCII.GetBytes(sKey);
                MemoryStream ms = new MemoryStream();
                CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
                cs.Write(inputByteArray, 0, inputByteArray.Length);
                cs.FlushFinalBlock();
                StringBuilder ret = new StringBuilder();
                foreach (byte b in ms.ToArray())
                {
                    ret.AppendFormat("{0:X2}", b);
                }
                ret.ToString();
                return ret.ToString();
            }
            catch
            {
                return "";
            }
        }
    }
}
